The aim of this study is to determine whether elderly patients with a dementing illness, but who are not depressed, differ, with respect to antecedants and outcome, from patients who are demented and also depressed. Dementia and depression are the most common severe psychiatric problems of the aged, yet there is little information on how often they occur together. Data from a preliminary study suggest that they coexist in 20 to 25% of cases of dementia, and that depression is more likely to occur in mild to moderate cases of dementia. Since depression is treatable, it is reasonable to ask whether demented patients who are depressed can improve in their cognitive ability with resolution of their depression. There will be 75 patients in each of 2 groups for a total of 150 subjects: Demented Only, and Demented-Plus-Depressed. Identification and assignment to these groups will be by simple clinical measures. Data will be collected on sex, age, previous psychiatric history, type of dementia, and living situation to determine if any of these predict the dementia - depression syndrome. A battery of cognitive and affective measures will be collected on entry and 3, months later, an interval during which subjects receive a treatment program that includes the tricyclic antidepressant imipramine, in order to determine whether the 2 groups have different outcomes regarding cognitive function. A one-year phone call followup will be used to estimate differences in mortality and rate of institutionalization. The study has important health implications if a subgroup of demented patients can be identified who improve when treated for depression.